Alternating/Simultaneous problems

[coyoteboy]

I have a 4 pot engine running port injection and MSnSE 29q on a 2.2 board. Running in two squirts alternating (Req_Fuel is 7. seems to run just fine, though the injectors seem noisier than normal. I decided to see if it would be ok running simultaneous 1 squirt. Runs like a dog, almost falls over - idle drops from 800 to 500 and it coughs and splutters. I have cyls 1 and 2 on one bank and 3 and 4 on the other bank. Any ideas why this could be - i would have thought it would have given no noticable difference, especially at idle? I'm not too worried as it runs ok as alternating but I just wondered if it was indicative of a problem?

Advice much appreciated.
J

[78Spit1500Fed]

...I decided to see if it would be ok running simultaneous 1 squirt. Runs like a dog...

Simultaneous, 1 squirt means all your fuel is being injected at once. At very low speeds (like idle) that means that there is quite a bit of fuel just sitting around waiting to be sucked in... the same goes for alternating, but it can help a bit in these cases.

It's better to increase the number of squirts per cycle. If you experience this problem... try simultaneous, 2 squirts or higher.

Also, this might be an indication that your open/close times are off a bit, or that your PWM settings need some tuning.

-Brian

[coyoteboy]

Ahh right, ok. I didnt want to go too many squirts per cycle as im thinking I'll be at the upper end of these injectors as it is (440s). I'll have to set the timings correctly - I'll go back and read the megamanual again before i try more squirts - see if i have missed something. I should be able to have the PWM current at 100% (low imp but with resistor pack) and i thought 1ms was pretty much normal for toyota injectors, maybe im missing something.

Ta

[Jedrik]

I have some 440 Supra injectors. I checked them on a scope and measured just under 1.1 ms open time... but I would leave yours at 1ms should not make a difference.

I noticed when playing with no. squirts and simultanious/alternating that I had to cycle MS on and off to make it "take". The it would atleast run long enought to adjust idle VE.

And it will still take some hand tweeking to get the mixtures right. So its not something you can just change around.

MAybe someone will make code that allows multiple squirts at idle and One squirt at power...

[MSBoostedEscort]

I have cyls 1 and 2 on one bank and 3 and 4 on the other bank.

if your firing order is 1342 and you have it set on alternating then wouldnt you have to have it set to... 1 4 on one bank and 2 3 on the other...

1......3......4......2
1,4..2,3...1,4.....2,3
A......B......A......B

[coyoteboy]

Erm well i asked this a while ago and I was told it made no odds, give or take a gnats bum, so i did i that way. Easy to change if its needed??

J

[MSBoostedEscort]

it does make a diffference. since it alternates you have to match up one bank with a alternating cylinder. if you have 1,2 A and 3,4 B then cyl 4 and 2 will miss its injection event

[Daryl]

"it does make a diffference. since it alternates you have to match up one bank with a alternating cylinder. if you have 1,2 A and 3,4 B then cyl 4 and 2 will miss its injection event"
 
Since this is batch, or bank fire and not timed to valve openings, how does a cylinder miss it's "injection event"?
 
Daryl

Posted by email.

[MSBoostedEscort]

well, this is how it worked on my car, i tried it both ways.


this would be for alternating 2 squirts.

if you have it set up to 1,4 and 2,3:

1......3......4......2 cyl
1,4..2,3...1,4.....2,3 inj
A......B......A......B bank

if you have it 1,2 and 3,4:

1......3......4......2 cyl
1,2..3,4...1,2....3,4 inj
A......B......A......B bank


notice the 1,3 cyl corrisponds to the first alternation of A B. the second alternation fires 2 wrong injectors.

[Daryl]

"well, this is how it worked on my car, i tried it both ways."
 
And did you notice a difference?

"notice the 1,3 cyl corrisponds to the first alternation of A B. the second alternation fires 2 wrong injectors."

Yes, I understand the timing of the injections, BUT, since it is not coincidental with valve openings, I don't think it will make much if any difference. Further, with 2 injections per ignition event (if I understand this correctly) would make it even less likely to have any noticeable effect.
 
Please correct me if I am wrong.
 
Daryl

Posted by email.